1. Field of the Invention
The present invention relates to thermo-siphon and its manufacturing method and an information processing apparatus. Particularly, the present invention relates to the information processing apparatus for releasing heat generated at a heat generation unit to outside.
2. Background Art
Conventionally, a technique relating to this field is disclosed in Japanese unexamined patent publication HEI 9-6481. The conventional mobile information processing apparatus mentioned in this publication as illustrated in FIG. 55 comprises a lid 51 incorporating a heat pipe 3 and a heat spreading board 5, and a main body 50 incorporating a heat generation unit (central processing unit) 1. The heat generated from the heat generation unit 1 is released from the heat spreading board 5 via a thermally conductive block 2.
Another conventional techniques relating to this field are Japanese unexamined patent publications HEI 8-87354, HEI 8-204373 and HEI 8-261672.
FIG. 56 illustrates a side view of disintegrated lid 51.
Following components are installed in between a front panel 60 and an external chassis 12: a liquid crystal display panel 7; a back light 10; a back light optical system 62; and a inverter circuit board 95 for the back light.
FIG. 57 illustrates a temperature profile of the lid 51 and the main body 50.
In the drawing, curved lines in the temperature profile illustrate isotherms. As can be seen from FIG. 57, a lot of heat is being generated from the CPU 1, the back light 10 and the inverter circuit board 95.
FIG. 58 illustrate a conventional manufacturing method of thermo-siphon used in heat spreading.
FIG. 59 illustrate a manufacturing step of roll bond heat pipe disclosed in the explanatory note published by Showa Aluminum Kabushiki Kaisha.
The roll bond is manufactured as follows: cutting aluminum plates (S10); printing a path to form a flow channel on top of an aluminum plate by using a pressure adhesion preventing agent (S12); place another aluminum plate on top of the aluminum plate for rolling them together (S13, S14); and inflate the flow channel using high-pressure gas and the thermo-siphon is cut into a desired shape (S15, S16). The thermo-siphon is manufactured by injecting a working fluid to this inflated flow channel.
The conventional mobile information processing apparatus has difficulty in conducting heat, which is sent from the heat pipe 3, throughout the heat spreading board due to an inadequate heat conduction to a direction of plane of the heat spreading board 5. As a result of this, from within various positions of the heat spreading board 5, only positions that are close to the heat pipe 3 were able to contribute in spreading the heat such that an effect of heat spreading in the conventional mobile information processing apparatus is therefore inadequate.
The conventional thermo-siphon is manufactured by pressurizing the two aluminum plates together, however, since a specific gravity of aluminumplate is heavy, a weight of the thermo-siphon will also become heavy. This results in a problem of increasing the weight of information processing apparatus when attempt to spread the heat using the thermo-siphon.
Also, in the conventional mobile information processing apparatus, from the back light which is installed at inner lateral plane of the lid, a heat is transferred to the liquid crystal display panel to cause difference in temperature at a position close to the back light and at a position far from the back light. Due to such a temperature difference, a color inconsistency of the back light 10 occurs which is a problem.